Same volt on inverting and non inverting input of Operational Amplifier

[muhammad11]

Question-1 what will happen if we apply Same volt on inverting and non inverting input of Operational Amplifier?
Question -2 : In above case how to get desired output?

 

[wwfeldman]

what circuit are you using with the op amp?
output likley depends on the inputs and the circuit.

if there are only the two inputs and power, then the output should be 0.
but there are always minor and usually ignore-able differences between the two input circuits.
there is the possibility of the op amp output going to either the positive rail or the negative rail,
like a comparator.

 

[KlausST]

Hi,

1) funny question. Often asked, often answered already.
Just do an internet search.

2) what is "desired"?

Klaus

 

[danadakk]

If you are applying V's directly to input pins thats not a good idea -

1) When device powers up possible to destroy inputs due to power sequencing issues.

2) If apply directly, same V, then OpAmp is operating open loop, so its G several hundred
thousand or more typically. But OpAmps, as stated by wwfeldman, have mismatched inputs.
This is called offset voltage. That Voff x Aol (open loop G) results in OpAmp acting like a comparator. So output would either be at - rail or + rails depending on sign of V offset.


Regards, Dana.

 

[dick_freebird]

1) AVOL*VIO
2) Trim

 

[muhammad11]

Hi,

1) funny question. Often asked, often answered already.
Just do an internet search.

2) what is "desired"?

Klaus

If you tell here it will be highly appreciable

 

[Easy peasy]

An op amp works by multiplying the difference between its inputs by the open loop gain ( at that freq, or DC, as may be the case )

if the voltage gain is 100,000, then 1uV difference = 100mV out, this is why the input offset figure is most important for high gain amplification of low value input signals.

 

[crutschow]

Question-1 what will happen if we apply Same volt on inverting and non inverting input of Operational Amplifier?

It will likely saturate with the output going to one output voltage rail or the other depending upon its input offset.

Question -2 : In above case how to get desired output?

Since we are not clairvoyant, how can we know what the "desired output" is?
If you tell us what it is, then perhaps we can help.